Ultraviolet radiation over two lakes in the middle and lower reaches of the yangtze river, ,China: An innovative model for UV estimation

This study aims to explore the characteristics of ultraviolet (UV) radiation over Dong Lake (DL) and Tai Lake (TL) in the middle and lower reaches of the Yangtze River and to develop an innovative model for UV estimation under all weather conditions. The characteristic analysis of UV radiation shows distinctly hourly and monthly variations at two typical sites. The maximum values can represent the hourly UV feature, and the median and the arithmetic mean values are reasonably similar with little difference for both stations. The monthly means of hourly UV radiation range from 25.68 to 70.07 kJ m(-2) for DL and between 36.00 and 92.62 kJ m(-2) for TL. The monthly mean hourly UV fractions vary from 3.79% to 4.93% at DL and between 4.57% and 5.94% at TL. Comparisons on the monthly mean hourly values of UV radiation and UV fraction, the values at TL are always greater than those at DL. An innovative model is constructed based on two input parameters, namely the effect of the comprehensive attenuation factors for assumed cloud-free conditions (CAF(UVclear)) and the effect of the clouds (K-g). CAF(UVclear) is derived from empirical models based on relative optical air mass and ozone. The effectiveness of the presented model is demonstrated by comparing with other two estimation models. This innovative model presents values of RMSE better than two reported models either at local place or a different locality. It indicates that this new model can provide satisfactory estimates of UV radiation at different localities other than the local place of origin where the relationships are developed.